The subject matter described herein relates to electronic communication, and more particularly to remote timing synchronization techniques which may be used in wireless communication systems.
Timing acquisition and synchronization is an important element of modem electronic systems, such as Digital Communications Systems, Radar Systems, and Digital Signal Processing Systems. The subject of receiver synchronization is discussed in many books on digital communications (see, for example, Sklar, B, Digital Communications, 2nd Ed., Chapter 10, Prentice Hall, Upper Saddle River, N.J., 2001), and, entire books have been written on the subject of receiver synchronization within digital communications systems (Mengali, U, Synchronization Techniques for Digital Receivers, Springer, New York, N.Y., 1997; Meyr, H. et al, Synchronization in Digital Communications, John Wiley & Sons, Hoboken, N.J., 1990), all of the foregoing books being hereby incorporated by reference. In many applications, such as the extremely dense signal environment of a cellular phone system, the low signal-to-noise-ratio communications channel of a deep space probe, or the very narrowband system employed by a digital modem in most personal computers, efficient signal synchronization techniques are desired. The act of synchronization within a receiver essentially involves replicating the timing information contained in the transmitted signal within the receiver, so that the data information modulated or encoded within the transmitted signal can be extracted. Without first obtaining synchronization, data information cannot be extracted from the transmitted signal, and the communications link will fail. Hence, timing acquisition is one of the first processes that takes place when a communications link between a receiver and a transmitter is established.
One technique employed in the systems mentioned above is the use of PN sequences for timing acquisition and synchronization. Additionally, due to improved clocks and the omnipresence of GPS, accurate time references are available at receivers for use in timing acquisition. Thus, when sending a PN sequence to achieve timing acquisition for many different applications that also have access to GPS and/or improved clocks, the timing uncertainty of these systems has been reduced.
Some existing timing and synchronization solutions use a code division multiple access (CDMA) type signal within a specific frequency band as a timing signal. Receivers synchronize to this signal using correlation techniques against a template for this CDMA signal. This structure restricts the timing signal to occupy a contiguous frequency band, requires a large and fast correlation unit to determine where the peak correlation is, is not robust against frequency dependent propagation effects and interference, and may be corrupted by signal multipath interference.
Accordingly, techniques for remote timing synchronization which may be used in wireless communication systems may find utility.